Shares closed at $5.94, up 94 cents, or almost 19 percent. Earlier today the shares rose to a high of nearly $7. The stock had fallen 78 percent in the past year on investors' concern that High Speed's subscriber growth will slow.
Allen, who co-founded Microsoft, was already the company's largest shareholder as part of his so-called wired-world plan to fund companies that provide high-speed online connections. His investment will increase his stake in Denver-based High Speed to 50 percent from 36 percent now, chief executive Dan O'Brien said.
''It's Paul Allen's way of showing that he has all the confidence in the world in this company,'' said JWGenesis Capital Markets analyst Allan Roness, who has a ''buy'' rating on High Speed. ''This is one of his babies, and it's closely affiliated with Charter.''
High Speed provides fast Internet service to customers of St. Louis-based Charter Communications, which Allen controls. Charter is one of the top U.S. cable companies.
Allen, 47, is the fourth richest person in the world, according to Forbes magazine. He has invested billions of dollars in cable TV, telecommunications and Internet companies.
Copyright 2000, Bloomberg L.P. All Rights Reserved.